This type of outboard motor equipped with a transmission mechanism is known in the industry, as disclosed in Japanese Patent Application Laid-Open Publication No. 2009-185972 (JP 2009-185972 A).
FIG. 5 hereof shows the outboard motor disclosed in JP 2009-185972 A.
As can be seen in FIG. 5, an outboard motor 200 is attached to a hull 202 by a swivel arm 201. A vertical engine 203 is disposed in an upper part of the outboard motor 200. Power from the engine 203 is transmitted to a transmission mechanism 206 via an input shaft 205 connected to a crankshaft 204. The power transmitted to the transmission mechanism 206 is transmitted to a propeller 209 via a propeller drive shaft 208 accommodated in a gear case 207.
Exhaust gas generated by the engine 203 is discharged to the exterior through an exhaust channel 211 provided inside a case 210. A lubricating oil pump 212 is disposed in an upper part of the transmission mechanism 206. The transmission mechanism 206 is disposed above the gear case 207.
An oil pan is usually disposed underneath the transmission mechanism 206. The oil used to lubricate the transmission mechanism 206 is recovered in the oil pan, and can be reused for lubrication by the oil pump 212.
However, the oil pump 212 is disposed in the upper part of the transmission mechanism 206 in the outboard motor shown in FIG. 5, making it necessary to raise the level of the oil in order for the oil to be drawn upward, and generating a certain amount of resistance. There has been a demand in recent years for further improvement in the power transmission efficiency of the transmission mechanism. It is accordingly desirable to increase the power transmission efficiency of the transmission mechanism while maintaining the lubrication performance.
In addition, the oil pump 212 and the oil pan are disposed separately from the exhaust channel 211 and are placed above the gear case 207. Having these components disposed one above the other raises the center of gravity of the outboard motor.